[Bug target/102478] New: [9/10/11/12 Regression] during RTL pass: ce3: ICE: in gen_reg_rtx, at emit-rtl.c:1167 with -O2 -fno-if-conversion

["zsojka at seznam dot cz" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102478

            Bug ID: 102478
           Summary: [9/10/11/12 Regression] during RTL pass: ce3: ICE: in
                    gen_reg_rtx, at emit-rtl.c:1167 with -O2
                    -fno-if-conversion
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: powerpc64le-unknown-linux-gnu

Created attachment 51508
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51508&action=edit
reduced testcase

Compiler output:
$ powerpc64le-unknown-linux-gnu-gcc -O2 -fno-if-conversion testcase.c 
testcase.c: In function 'foo':
testcase.c:6:45: warning: division by zero [-Wdiv-by-zero]
    6 |   c |= __builtin_expect (65535 / a, 0) && 0 / 0;
      |                                             ^
during RTL pass: ce3
testcase.c:8:1: internal compiler error: in gen_reg_rtx, at emit-rtl.c:1167
    8 | }
      | ^
0x63b466 gen_reg_rtx(machine_mode)
        /repo/gcc-trunk/gcc/emit-rtl.c:1167
0xba8069 force_reg(machine_mode, rtx_def*)
        /repo/gcc-trunk/gcc/explow.c:676
0xe48e63 prepare_cmp_insn
        /repo/gcc-trunk/gcc/optabs.c:4396
0xe4a09f gen_cond_trap(rtx_code, rtx_def*, rtx_def*, rtx_def*)
        /repo/gcc-trunk/gcc/optabs.c:5851
0x19548e7 find_cond_trap
        /repo/gcc-trunk/gcc/ifcvt.c:4721
0x19548e7 find_if_header
        /repo/gcc-trunk/gcc/ifcvt.c:4346
0x19548e7 if_convert
        /repo/gcc-trunk/gcc/ifcvt.c:5475
0x195565d execute
        /repo/gcc-trunk/gcc/ifcvt.c:5628
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

$ powerpc64le-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-powerpc64le/bin/powerpc64le-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r12-3885-20210924181655-g71f96511084-checking-yes-rtl-df-extra-powerpc64le/bin/../libexec/gcc/powerpc64le-unknown-linux-gnu/12.0.0/lto-wrapper
Target: powerpc64le-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl
--with-sysroot=/usr/powerpc64le-unknown-linux-gnu --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=powerpc64le-unknown-linux-gnu
--with-ld=/usr/bin/powerpc64le-unknown-linux-gnu-ld
--with-as=/usr/bin/powerpc64le-unknown-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r12-3885-20210924181655-g71f96511084-checking-yes-rtl-df-extra-powerpc64le
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.0.0 20210924 (experimental) (GCC)